1. Field
Exemplary embodiments of the invention relate to a method of driving a light-source, and a display apparatus for performing the method of driving the light-source. More particularly, exemplary embodiments of the invention relate to a method of driving a light-source with improved contrast ratio, and a display apparatus for performing the method of driving the light-source.
2. Description of the Related Art
Generally, a liquid crystal display (“LCD”) apparatus includes an LCD panel that displays an image using optical transmittance of liquid crystal molecules and a backlight assembly disposed below the LCD panel to provide the LCD panel with light.
The LCD panel includes an array substrate, a color filter substrate and a liquid crystal layer. The array substrate includes a plurality of pixel electrodes and a plurality of thin-film transistors (“TFTs”) electrically connected to the pixel electrodes. The color filter substrate faces the array substrate and has a common electrode and a plurality of color filters. The liquid crystal layer is interposed between the array substrate and the color filter substrate. When an electric field generated between the pixel electrode and the common electrode is applied to the liquid crystal layer, the arrangement of liquid crystal molecules of the liquid crystal layer is altered to change the optical transmissivity of the liquid crystal layer, such that an image is displayed on the LCD panel. The LCD panel displays a white image of a high luminance when an optical transmittance is increased to maximum, and the LCD panel displays a black image of a low luminance when the optical transmittance is decreased to minimum.
Recently, the backlight assembly includes a plurality of light-emitting diodes (“LEDs”) as a light-source. Light emitted from the LEDs is controlled using a pulse width modulation (“PWM”) dimming method based on luminance of an image displayed on the LCD panel. According to the PWM dimming method, a duty ratio of a pulse is adjusted to adjust an intensity of the light emitted from the LEDs. In the PWM dimming method, when the duty ratio of the pulse is less than about 2%, a high level of a current outputted from the LED is substantially decreased, and the LED is thereby not effectively controlled.